fix(txe): align tagging strategy oracle with PXE

docs/docs-developers/docs/foundational-topics/pxe/execution_hooks.md

@@ -82,14 +82,19 @@ For an unconstrained self-send (the recipient is one of the wallet's own account
 
 ### In Noir tests
 
-When testing in Noir, leaving the strategy unset makes `TestEnvironment` fall back to the bare PXE default. Set a strategy when creating the environment to exercise a specific one; it affects message delivery in private executions:
+When testing in Noir, leaving the strategy unset makes `TestEnvironment` fall back to the bare PXE default. Set a strategy when creating the environment to exercise a specific one; it affects message delivery in private executions. Use `with_tag_secret_strategy` to configure the strategy for a specific delivery mode:
 
 ```rust
 let env = TestEnvironment::new_opts(
-    TestEnvironmentOptions::new().with_tagging_secret_strategy(TaggingSecretStrategy::non_interactive_handshake()),
+    TestEnvironmentOptions::new().with_tag_secret_strategy(
+        MessageDelivery::onchain_unconstrained(),
+        TaggingSecretStrategy::non_interactive_handshake(),
+    ),
 );
 ```
 
+Use `with_tag_secret_strategy_all_modes` only when the same strategy should apply to both constrained and unconstrained delivery.
+
 ### In production
 
 Pass a `resolveTaggingSecretStrategy` hook when [creating the PXE](#configuring-hooks). It receives a `TaggingSecretStrategyRequest` with the executing contract's address and the message's sender, recipient, and delivery mode (`'constrained'` or `'unconstrained'`), so a wallet can apply per-application or per-recipient policies, or surface the decision to the user, instead of returning a fixed value.

noir-projects/aztec-nr/aztec/src/messages/delivery/tag.nr

@@ -180,6 +180,29 @@ mod test {
         });
     }
 
+    #[test(should_fail_with = "an unconstrained tagging secret cannot back constrained delivery")]
+    unconstrained fn constrained_delivery_rejects_a_resolved_unconstrained_secret() {
+        let env = TestEnvironment::new();
+        let secret: Field = 7;
+        let index: u32 = 0;
+
+        env.private_context(|context| {
+            mock_existing_handshake_secrets(Option::none());
+            let _ = OracleMock::mock("aztec_prv_resolveTaggingStrategy").returns(
+                ResolvedTaggingStrategy::unconstrained_secret(secret),
+            );
+            let _ = OracleMock::mock("aztec_prv_getNextTaggingIndex").returns(index);
+
+            let _ = derive_log_tag(
+                context,
+                OnchainDeliveryMode::onchain_constrained(),
+                SENDER,
+                RECIPIENT,
+                Option::none(),
+            );
+        });
+    }
+
     #[test]
     unconstrained fn constrained_delivery_emits_the_sequence_nullifier_and_constrained_tag() {
         let env = TestEnvironment::new();

noir-projects/aztec-nr/aztec/src/test/helpers/mod.nr

@@ -13,7 +13,7 @@ pub mod test_environment;
         quote { private_call_new_flow_oracle }, // TODO: implement once we support more complex types
         quote { public_call_new_flow_oracle }, // TODO: implement once we support more complex types
         quote { set_private_txe_context_oracle }, // TODO: implement once we support more complex types
-        quote { set_tagging_secret_strategy }, // TODO: implement once we support more complex types
+        quote { set_tagging_secret_strategies }, // TODO: implement once we support more complex types
     ],
 )]
 pub mod txe_oracles;

noir-projects/aztec-nr/aztec/src/test/helpers/tagging_secret_strategy.nr

@@ -1,4 +1,11 @@
-use crate::protocol::{point::EmbeddedCurvePoint, traits::{Deserialize, Serialize}, utils::reader::Reader};
+use crate::keys::ecdh_shared_secret::compute_app_siloed_shared_secret;
+use crate::protocol::{
+    address::AztecAddress,
+    hash::poseidon2_hash,
+    point::EmbeddedCurvePoint,
+    traits::{Deserialize, Serialize, ToField},
+    utils::reader::Reader,
+};
 
 global NON_INTERACTIVE_HANDSHAKE: u8 = 1;
 global ARBITRARY_SECRET: u8 = 2;
@@ -7,7 +14,7 @@ global INTERACTIVE_HANDSHAKE: u8 = 4;
 
 /// How a message's tagging secret is chosen: the wallet's strategy.
 ///
-/// This type only exists for tests: a Noir test sets it via `with_tagging_secret_strategy` on
+/// This type only exists for tests: a Noir test sets it via `with_tag_secret_strategy` on
 /// [`TestEnvironmentOptions`](crate::test::helpers::test_environment::TestEnvironmentOptions).
 /// Production wallets express the strategy in PXE; the Noir path only consumes the resolved
 /// [`ResolvedTaggingStrategy`](crate::messages::delivery::ResolvedTaggingStrategy).
@@ -45,18 +52,26 @@ impl TaggingSecretStrategy {
     /// Validates a raw discriminant, as deserialization must always reject unknown values.
     fn from_parts(kind: u8, secret: EmbeddedCurvePoint) -> Self {
         let strategy = Self { kind, secret };
+        let is_no_payload_strategy =
+            (kind == NON_INTERACTIVE_HANDSHAKE) | (kind == INTERACTIVE_HANDSHAKE) | (kind == ADDRESS_DERIVED);
         assert(
-            (
-                ((kind == NON_INTERACTIVE_HANDSHAKE) | (kind == ADDRESS_DERIVED) | (kind == INTERACTIVE_HANDSHAKE))
-                    & secret.is_infinite()
-            )
-                | (kind == ARBITRARY_SECRET),
+            (is_no_payload_strategy & secret.is_infinite()) | (kind == ARBITRARY_SECRET),
             f"unrecognized tagging secret strategy kind: {kind}",
         );
         strategy
     }
 }
 
+/// Computes the directional tagging secret PXE derives from an arbitrary shared secret point: the point is app-siloed
+/// and the recipient is folded in for direction. Mirrors `AppTaggingSecret.computeDirectional` on the PXE side; tests
+/// use it to derive the secret they expect an [`arbitrary_secret`](TaggingSecretStrategy::arbitrary_secret) strategy
+/// to produce.
+pub fn compute_directional_app_secret(secret: EmbeddedCurvePoint, app: AztecAddress, recipient: AztecAddress) -> Field {
+    poseidon2_hash(
+        [compute_app_siloed_shared_secret(secret, app), recipient.to_field()],
+    )
+}
+
 impl Deserialize for TaggingSecretStrategy {
     let N: u32 = 3;
 
@@ -81,14 +96,14 @@ mod test {
     #[test]
     fn strategy_roundtrips_through_serialization() {
         let non_interactive = TaggingSecretStrategy::non_interactive_handshake();
+        let interactive = TaggingSecretStrategy::interactive_handshake();
         let address = TaggingSecretStrategy::address_derived();
         let provided = TaggingSecretStrategy::arbitrary_secret(EmbeddedCurvePoint { x: 7, y: 11 });
-        let interactive = TaggingSecretStrategy::interactive_handshake();
 
         assert(TaggingSecretStrategy::deserialize(non_interactive.serialize()) == non_interactive);
+        assert(TaggingSecretStrategy::deserialize(interactive.serialize()) == interactive);
         assert(TaggingSecretStrategy::deserialize(address.serialize()) == address);
         assert(TaggingSecretStrategy::deserialize(provided.serialize()) == provided);
-        assert(TaggingSecretStrategy::deserialize(interactive.serialize()) == interactive);
     }
 
     #[test(should_fail_with = "unrecognized tagging secret strategy kind")]
@@ -98,16 +113,22 @@ mod test {
 
     #[test(should_fail_with = "unrecognized tagging secret strategy kind")]
     fn deserializing_handshake_with_noninfinite_point_fails() {
-        let _ = TaggingSecretStrategy::deserialize([1, 7, 11]);
+        let _ = TaggingSecretStrategy::deserialize([
+            TaggingSecretStrategy::non_interactive_handshake().kind as Field,
+            7,
+            11,
+        ]);
     }
 
     #[test(should_fail_with = "unrecognized tagging secret strategy kind")]
     fn deserializing_address_derived_with_noninfinite_point_fails() {
-        let _ = TaggingSecretStrategy::deserialize([3, 7, 11]);
+        let _ = TaggingSecretStrategy::deserialize(
+            [TaggingSecretStrategy::address_derived().kind as Field, 7, 11],
+        );
     }
 
     #[test(should_fail_with = "unrecognized tagging secret strategy kind")]
     fn deserializing_interactive_handshake_with_noninfinite_point_fails() {
-        let _ = TaggingSecretStrategy::deserialize([4, 7, 11]);
+        let _ = TaggingSecretStrategy::deserialize([TaggingSecretStrategy::interactive_handshake().kind as Field, 7, 11]);
     }
 }

noir-projects/aztec-nr/aztec/src/test/helpers/test_environment.nr

@@ -13,6 +13,7 @@ use crate::{
     event::{event_interface::EventInterface, EventMessage},
     hash::{compute_secret_hash, hash_args},
     messages::{
+        delivery::OnchainDeliveryMode,
         discovery::{
             ComputeNoteHash, ComputeNoteNullifier, CustomMessageHandler, process_message::process_message_plaintext,
         },
@@ -88,28 +89,53 @@ pub struct TestEnvironment {
 /// methods setting each value, e.g.:
 /// ```noir
 /// let env = TestEnvironment::new_opts(
-///     TestEnvironmentOptions::new().with_tagging_secret_strategy(TaggingSecretStrategy::non_interactive_handshake()),
+///     TestEnvironmentOptions::new().with_tag_secret_strategy(
+///         MessageDelivery::onchain_unconstrained(),
+///         TaggingSecretStrategy::non_interactive_handshake(),
+///     ),
 /// );
 /// ```
 pub struct TestEnvironmentOptions {
-    tagging_secret_strategy: Option<TaggingSecretStrategy>,
+    unconstrained_tagging_secret_strategy: Option<TaggingSecretStrategy>,
+    constrained_tagging_secret_strategy: Option<TaggingSecretStrategy>,
 }
 
 impl TestEnvironmentOptions {
     /// Creates a new `TestEnvironmentOptions` with default values.
     pub fn new() -> Self {
-        Self { tagging_secret_strategy: Option::none() }
+        Self {
+            unconstrained_tagging_secret_strategy: Option::none(),
+            constrained_tagging_secret_strategy: Option::none(),
+        }
     }
 
-    /// Sets the [`TaggingSecretStrategy`] the wallet reports through the
+    /// Sets the [`TaggingSecretStrategy`] the wallet reports for `mode` through the
     /// [`resolve_tagging_strategy`](crate::oracle::resolve_tagging_strategy) oracle, affecting message delivery in
     /// private executions.
     ///
-    /// If not set, the wallet hook is left unconfigured and the private execution environment applies its own default.
-    pub fn with_tagging_secret_strategy(&mut self, strategy: TaggingSecretStrategy) -> Self {
-        self.tagging_secret_strategy = Option::some(strategy);
+    /// If no strategy is set for either mode, the wallet hook is left unconfigured and the private execution
+    /// environment applies its own default. A mode left unset while the other is configured falls back to the default
+    /// [`TaggingSecretStrategy::non_interactive_handshake`], the strategy a PXE `resolveTaggingSecretStrategy` hook
+    /// typically hardcodes for modes it does not customize.
+    pub fn with_tag_secret_strategy<M>(&mut self, mode: M, strategy: TaggingSecretStrategy) -> Self
+    where
+        M: Into<OnchainDeliveryMode>,
+    {
+        if mode.into() == OnchainDeliveryMode::onchain_unconstrained() {
+            self.unconstrained_tagging_secret_strategy = Option::some(strategy);
+        } else {
+            self.constrained_tagging_secret_strategy = Option::some(strategy);
+        }
         *self
     }
+
+    /// Sets `strategy` for both delivery modes: the equivalent of a PXE `resolveTaggingSecretStrategy` hook that
+    /// ignores the request's mode. See [`with_tag_secret_strategy`](Self::with_tag_secret_strategy) to configure a
+    /// single mode.
+    pub fn with_tag_secret_strategy_all_modes(&mut self, strategy: TaggingSecretStrategy) -> Self {
+        let _ = self.with_tag_secret_strategy(OnchainDeliveryMode::onchain_unconstrained(), strategy);
+        self.with_tag_secret_strategy(OnchainDeliveryMode::onchain_constrained(), strategy)
+    }
 }
 
 /// Configuration values for [`TestEnvironment::private_context_opts`]. Meant to be used by calling `new` and then
@@ -607,18 +633,19 @@ impl TestEnvironment {
     ///
     /// ### Sample usage
     /// ```noir
+    /// let strategy = TaggingSecretStrategy::non_interactive_handshake();
     /// let env = TestEnvironment::new_opts(
-    ///     TestEnvironmentOptions::new().with_tagging_secret_strategy(
-    ///         TaggingSecretStrategy::non_interactive_handshake(),
-    ///     ),
+    ///     TestEnvironmentOptions::new().with_tag_secret_strategy_all_modes(strategy),
     /// );
     /// ```
     pub unconstrained fn new_opts(options: TestEnvironmentOptions) -> Self {
         assert_compatible_oracle_version();
         txe_oracles::assert_compatible_txe_oracle_version();
 
-        // Forward the configured strategy to the wallet.
-        txe_oracles::set_tagging_secret_strategy(options.tagging_secret_strategy);
+        txe_oracles::set_tagging_secret_strategies(
+            options.unconstrained_tagging_secret_strategy,
+            options.constrained_tagging_secret_strategy,
+        );
 
         Self {
             // Use an offset to avoid secret collision with account secrets. Without this, when